1. Field of the Invention
The present invention relates to an optical disk apparatus adapted to perform at least one of recording and reproducing of information on and from an optical disk by using an optical pickup.
2. Description of the Related Art
Optical disk apparatuses, such as CD-ROM/R/RW drives and DVD-ROM/RAM/R/RW drives, have already been put into practical use. Application of optical disk apparatuses to various fields, and development of high-performance optical disk apparatuses are actively performed. Especially, recently, as personal-computer market has rapidly expands, the percentage of personal computers with built-in optical disk apparatuses has been increased. A method of pulling out a tray from a housing, and then mounting an optical disk on the tray, and subsequently returning the tray into the housing (hereunder referred to as a method of the “tray type”) is usually employed as a method of mounting an optical disk apparatus in an electronic apparatus. Hereinafter, description is given of the configuration of a related tray type optical disk apparatus by referring to FIGS. 7 and 8.
FIG. 7 is an external view of the related optical disk apparatus. In FIG. 7, reference numeral 1 designates the optical disk apparatus. Reference numeral 2 denotes a housing. Reference character 2a designates an upper housing portion. Reference character 2b denotes a lower housing portion. Reference numeral 3 designates a tray. Reference numeral 4 denotes an optical pickup module. Reference numeral 5 designates a rail. Reference character 6a denotes a housing-side rail holding portion. Reference character 6b designates a tray-side rail holding portion. Reference numeral 7 denotes a spindle motor. Reference character 7a designates an optical disk mounting portion. Reference numeral 8 denotes a metallic cover. Reference character 8a designates an opening. Reference numerals 9, 10, 11, and 12 denote a carriage, a bezel, an eject button, and an optical pickup, respectively.
The optical disk apparatus 1 has the housing 2, and the tray 3 retractably held in the housing 2. The housing 2 is formed like a container by combining the metallic upper housing portion 2a with the lower housing portion 2b. The tray 3 is drawn out of and retracted into the opening of the housing 2. The optical pickup module 4 is attached to the back surface of the tray 3. The rail 5 is movably provided on both sides of the tray 3. The rail 5 is held by the tray-side rail holding portion 6b provided integrally with the tray 3. Incidentally, although FIG. 7 shows that the rail 5 is provided on only one of side surface portions of the tray 3, a similar rail may be provided on the other side surface portion. The upper housing portion 2a and the lower housing portion 2b are securely fixed to each other by catching means (not shown) and screws (not shown).
The optical pickup module 4 has at least the spindle motor 7, which is adapted to rotate-drive an optical disk, and the metallic cover 8 provided with an opening 8a extending from the spindle motor 7 to the outer periphery thereof, and the carriage 9 partly exposed from the opening 8a. The carriage 9 is movably held by plural guide shafts provided in the optical pickup module 4. Additionally, the carriage 9 can be moved by a feed motor to get close to and away from the spindle motor 7.
Reference numeral 10 designates the bezel provided on the front surface of the tray 3. The bezel 10 has a size sufficient to the extent that the opening of the housing 2 is closed. A light source such as a high-output laser diode, various optical members and an objective lens adapted to form a light spot are mounted on the carriage 9. A circuit board is fixedly provided in an inner part of the housing 2. A signal processing system IC and a power supply circuit are mounted on the circuit board. A flexible cable connecting circuit boards (not shown) provided on the tray 3 is substantially U-shaped. An external connector is connected to power-supply/signal-line provided in an electronic apparatus, such as a computer. Electric power is supplied to the optical disk apparatus 1 through this external connector. Alternatively, external signals are introduced into the optical disk apparatus 1 through the external connector. Alternatively, electrical signals generated in the optical disk apparatus 1 are outputted to an electronic apparatus through the external connector. An eject button 11 is provided in the bezel 10 provided on the front surface of the tray 3. The engagement between an engaging portion provided in the housing 2 and that provided in the tray 3 is canceled by pushing this eject button 11. Thus, the tray 3 can be drawn out from the housing 2 thereby to dismount an optical disk therefrom and to mount an optical disk thereon.
FIG. 8 is a view showing the bezel and an electrically conductive cloth of the related optical disk apparatus. This figure shows a main flat portion provided opposite to the surface on which the eject button 11 is provided. Further, this figure shows that one of two flat portions is partly covered with both a metallic plate 14 and the conductive cloth 13. In FIG. 8, reference numerals 10, 13, and 14 designate the bezel, the conductive cloth, and the metallic plate, respectively. The conductive cloth 13 is an electrically conductive cloth material and has effects of shielding electromagnetic waves and so on. The metallic plate 14 is formed substantially like a flat plate by using an electrically conductive material, such as a stainless steel. The metallic plate 14 is intended to be a countermeasure against static electricity affecting the optical disk apparatus 1 through the eject button 11. The bezel 10 is combined with the upper housing portion 2a and the lower housing portion 2b to thereby close the opening of the container-like housing 2. Thus, the bezel 10 serves to prevent dust from entering the housing 2 and to prevent a user from touching the inside of the optical disk apparatus 1. Simultaneously, it is necessary for the bezel 10 to prevent electromagnetic waves generated by other electronic apparatuses, such as a portable phone, from entering the optical disk apparatus 1 to thereby cause malfunctions and troubles of the optical disk apparatus 1. Thus, generally, countermeasures against external electromagnetic waves are applied to the entire surface of the main flat portion provided opposite to the surface, on which the eject button 11 is provided, in the bezel 10. Usually, the metallic plate 14 serving as a countermeasure against static electricity, which affects the optical disk apparatus 1 when a user pushes the eject button 11, is provided only in the vicinity of the eject button 11 in the main flat portion provided opposite to the surface, on which the eject button 11 is provided, in the bezel 10. Thus, the rest of this main flat portion is covered with the conductive cloth 13. In a case where the conductive cloth 13 is not provided in the bezel 10, and where external electromagnetic waves enter the optical disk apparatus 1, an actuator coil of the optical pickup 12 performs resonant oscillations. Consequently, the following malfunctions and troubles occur. That is, the movement of the optical pickup 12 cannot be controlled. A malfunction of a laser power detecting means of the optical pickup 12 occurs, so that laser power cannot be controlled. Noises are caused in signals through the pattern formed on the circuit board and the flexible cable.
Related art is disclosed in JP9-326191.
To prevent external electromagnetic waves from entering the optical disk apparatus 1, it is necessary to apply countermeasures to the housing 2 and the bezel 10, which cover the entire optical disk apparatus 1. The housing 2 is usually made of an electrically conductive metallic material and has no problems. However, the bezel 10 is usually made of a resin material, which is the same as the material of the exterior of a personal computer, so as to establish unity of design between the bezel 10 and the personal computer in which the bezel 10 is mounted. Therefore, the conductive cloth 13 is added to the portion that is not covered with the metallic plate 14 serving as the countermeasure against static electricity, which is applied to an inner side of the bezel 10, that is, applied to the main flat portion placed opposite to the surface provided with the eject button 11, to thereby prevent electromagnetic waves from entering the optical disk apparatus 1 through the main flat portion of the bezel 10.
However, in a case where the bezel 10 is covered with both the metallic plate 14 and the conductive cloth 13 shown in FIG. 8, it is necessary to bring a part of the conductive cloth 13, which covers the bezel 10, into contact with the housing 2 thereby to assure a grounding line. An operation of attaching the conductive cloth 13 to the bezel 10, which is performed so as to reliably put the conductive cloth 13 into contact with the housing 2, is very difficult. This results in reduction of productivity. Additionally, because the conductive cloth 13 is made of cloth, it is difficult to control the position of the conductive cloth 13. Consequently, variation in the electromagnetic wave shielding characteristics is caused.